This invention relates to methods and apparatus for testing cables used in telephone, communication, video cables, and computer networks for identification of cable location and for a number of wire faults, such as (1) shorts between wires (2) open wires (3) improper connection of wires to terminating plugs, and (4) reversed wired terminating plugs.
During the installation of and interconnection of various equipment in telephone, video, and computer networks, it is necessary to make frequent wiring checks as to the integrity of connections made by means of exchange cable which is utilized to interconnect the various equipment. In many instances cable connectors are installed at the site of use using hand tools and special connectors. It is necessary that the cable be checked for proper connection of the plug terminals and identified as to its remote location when connected to the computer hub, telephone KSU (Key Switching Unit), or video distribution box.
A number of test facilities have been developed for making a number of checks of cable with connectors on ends so as to ascertain shorts, continuity and proper wire interconnection. One such test facilities is shown in U.S. Pat. No. 3,492,571 to D. A. Desler assigned to the Western Electric Co., Inc., where a multi-conductor cable having plugs at opposite ends is checked for shorts, opens and wires that are misconmected or cross-connected between terminals at the respective plug ends of the cable. This test facility includes means for sequentially applying test pulses to terminals at one plug end and sensing the receipt of the signals at the second plug end. The received signals are then compared with signals generated by a reference program circuit. The signals from the plug end of the wire and the reference circuit are applied to a comparison circuit to determine correctness, and if the signals do not properly compare then error signals are generated. The error signals are utilized to operate visual displays that provide information as to the faulty wires and the type of error determined by the comparison circuit.
There is a need for a lightweight, portable test unit for checking cables and cable wiring on a users site that can be transported, set up and run by a single operator. In each site or office such a test unit should be able to test for shorts between wires, open wires and misconnected or cross-connected wires, and this test unit should also have the capability of identifying the location of the remote terminated end of the cable under test. In addition, the test unit must be easy to use and user friendly.
This invention contemplates, among other things, methods and apparatus for conducting a number of tests on cables such as improper wire or cross wire connections, open wire conditions, actual remote plug wiring, and remote plug location.
More particularly, an operator determines a name for the location of the end of a cable to be terminated. This name could be as simple as a room number or as complex as a floor number, company name, office area, and desk number. This name could then be recorded onto a sheet of paper next to a load number (i.e. Load1=3rd floor, office 3, desk 2), or the load could be plugged into the test unit and the location name could be recorded into the memory of the test unit using speech (i.e. record button is pressed and operator says xe2x80x9cThird floor, office three, desk twoxe2x80x9d). The associated load is then connected to the cable at that location. This process is repeated for a number of loads.
The operator then proceeds to the originating point of the cables to be tested, usually a computer hub, video cable box, or Telephone Key Switching Unit (KSU). Cable integrity should be tested first to insure other readings are not corrupted by a cable fault. The test unit is then placed into the mapping mode and each cable is tested wire by wire for proper termination, no open wires, and no shorted wires. This process is repeated until the integrity of each cable has been verified.
The operator then places the test unit into the locating mode and connects a cable to be identified to the test unit.
During this test, the operator presses play and the test unit plays the previous recorded message associated with the load on the end of the cable now connected to the test unit. Or the operator checks the light indicating the load number and checks his written log to see what is written by that load number to determine the location of the remote end of the cable. Both methods are simple and user friendly requiring no deep understanding of electronics or transmission technology.
In the situation where a faulty wire is detected and the fault is due to an open or shorted condition, the location feature may still function provided the short or open is not on the pair being used to identify the cable location. The cable should then be repaired and tested again. In the case where a fault is on the pair being used to identify the cable, the process of elimination can be used to identify all good cables first, then proceed to repair the cables that were not identifiable.
Other features and advantages of the invention will be apparent upon consideration of the following detailed description and appended claims taken in conjunction with the accompanying drawings.